WMLScript Primer: WMLScript Libraries

WMLScript Primer

WMLScript Libraries

Like most compiled languages, WMLScript's functionality is based on a set of pre-compiled libraries that you can use in your scripts. As you well know, JavaScript's capabilities stem from its objects and their methods. WMLScript, on the other hand, does not support objects, and hence needs to rely on some other mechanism for functions. This other method is WMLScript Standard Libraries. We'll devote a separate column to these run-time libraries. Here, we'll give you an idea what kind of functions are included and how to use them. WMLScript features six libraries: Lang, Float, String, URL, WMLBrowser, and Dialogs.

The String library contains a set of string functions. A string is an array of characters. Each of the characters has an index, starting at 0. Notice that WMLScript does not feature the JavaScript's Array object. The String functions are: length(), isEmpty(), charAt(), subString(), find(), replace(), elements(), elementAt(), removeAt(), replaceAt(), insertAt(), squeeze(), trim(), compare(), toString(), and format(). Notice the wealth of functions that mimic array operations in JavaScript.

The WMLBrowser library contains functions by which WMLScript can access variables in the WML deck that called the WMLScript script. The Mortgage example shown later in this column includes a few calls to functions from this library. The functions are: getVar(), setVar(), go(), prev(), newContext(), getCurrentCard(), and refresh().

The Dialogs library contains a set of typical user interface functions. They are: prompt(), confirm(), and alert().

The following table shows four example functions from two of the above WMLScript libraries: